Method of tuning an electronic keyboard instrument in pure scale and apparatus therefor

ABSTRACT

Method and apparatus for tuning an electronic keyboard instrument in pure scale are disclosed herein. The apparatus comprises frequency modifier means such as potentiometers which are electrically associable with the normal tone generators of the instrument, said frequency modifier means being adjustable so as to influence a tone produced by said generator to have a particular frequency or pitch, and switching means for grouping said frequency modifier means for playing in a particular key. The switch means may be mechanical or electronic and a plurality of frequency modifier means are provided for each tone generator, preferably 12. The method of tuning the instrument in pure scale comprises providing the instrument with the tone generators in tune, electrically associating the frequency modifiers with the tone generators and thereafter tuning each generator in selected keys. The instrument will then play in pure scale in any particular key that is selected by the switch means. Additionally, a further set of frequency modifier means may be provided for selectively enabling the instrument to play in tempered scale.

United States Patent [191 Wells et al.

[ Mar. '18, 1975 METHOD OF TUNING AN ELECTRONIC KEYBOARD INSTRUMENT INPURE SCALE AND APPARATUS THEREFOR [75] Inventors: Ronald K. Wells,Spartanburg;

Charles W. Allen, Greenville, both of SC.

[73] Assignee: Ronald K. Wells, Spartensburg, SC.

[22] Filed: Dec. 11, 1972 [21] Appl. No.: 314,016

Primary E.\'aminer-Richard B. Wilkinson Assistant E.\'aminer-U. WeldonAttorney, Agent, or Firm-We11ington M. Manning, Jr.

[57] ABSTRACT Method and apparatus for tuning an electronic keyboardinstrument in pure scale are disclosed herein. The apparatus comprisesfrequency modifier means such as potentiometers which are electricallyassociable with the normal tone generators of the instrument, saidfrequency modifier means being adjustable so as to influence a toneproduced by said generator to have a particular frequency or pitch, andswitching means for grouping said frequency modifier means for playingin a particular key. The switch means may be mechanical or electronicand a plurality of frequency modifier means are provided for each tonegenerator, preferably 12. The method of tuning the instrument in purescale comprises providing the instrument with the tone generators intune, electrically associating the frequency modifiers with the tonegenerators and thereafter tuning each generator in selected keys. Theinstrument will then play in pure scale in any particular key that isselected by the switch means. Additionally, a further set of frequencymodifier means may be provided for selectively enabling the instrumentto play in tempered scale.

6 Claims, 8 Drawing Figures SUPPLY [52] US. Cl 84/101, 84/1.1l, 84/1.l9,84/107, 84/104 [51] Int. Cl. ..G10h U110 [58] Field 01' Search 84/101,1.17, 1.22, 1.24, 84/1.ll,1.19,1.07,1.04;33l/117 R, 179, 177 R [56]References Cited UNITED STATES PATENTS 2,403,664 7/1946 Langer 84/D1G.20 2,905,905 9/1959 George 84/].01 X 2,906,959 9/1959 Peterson....331/48 2,997,908 8/1961 Hilborn 84/101 3,295,070 12/1966 Tewksbury eta1. 331/179 3,401,229 9/1968 Kawabata et al. 84/1.l9 X 3,538,450 11/1970Andrea et al. 331/179 X 3,659,031 4/1972 Adachi 331/179 X 3,715,4442/1973 Pearlman 84/101 TO POSITIVE SUPPLY THROUGH SWITCHING NETWORK TOPOSmvE 0: 51 C3 2 3C1 TO NEGATlVE SUPPLY THROUGH swlTCl-llNG NETWORK ToNEGATIVE SUPPLY GROUND REFERENCE PLANE- PATENTEUHAR I 81975 SHEET 2 UP 76250.: Sw IQDOKI...

PATENTEU MAR l 8 I975 52556 wzok Q sum 3 or 7 G' BY V BI Q I II sum 6 of7 PATENTEBNAR] 8 ms sum 7 pg 7 51.5w m mztwom v u m v v bninm METHOD OFTUNING AN ELECTRONIC KEYBOARD INSTRUMENT IN PURE SCALE AND APPARATUSTHEREFOR BACKGROUND OF THE INVENTION Pure or just intonation is not anew idea per se, but has been studied throughout the years. For example,Hemholtz described an organ in the 1800s that would play in pure scale.This particular organ, however, was a manual keyboard instrument with alarge number of digitals per octave. Obviously, the instrument wasunwieldy due to the large number of digitals and could not beeffectively played.

Pointing to the derivation of pure or just intonation, the westerndiatonic scale is a group of tones related to each other by small wholenumbers, and was used many years ago for tuning keyboard instruments. Asmusic and musical instruments became more elaborate, the diatonic scalewas expanded to the chromatic scale. Further, as music and harmonyprogressed, composers began to write in different keys within the samework. For certain instruments no particular problem was encountered whenpitch was adjusted slightly to insure that the tonal relationshipsremain correct in a new key. With conventional digitalized instruments,however, such as the pipe organ or pianoforte, the pitch of each note isfixed, and once the instrument is tuned in a particular key and playedin yet another key, objectional beats result due to interaction of theharmonic of the notes being played which are not perfectly in tune.

Numerous tuning systems have been developed to minimize theout-of-tuneness referred to above. The equally tempered system hasvirtually gained universal acceptance in this regard, but does noteliminate the beats. Instead, the equal tempered scale merely minimizesout-of-tuneness by spreading the error across an entire octave. Theequal tempered sytem is utilized today for tuning digitalizedinstruments with the frequency interral between each note beingrepresented by the 12th root of 2.

While as mentioned above, an enormous number of separate keys necessaryfor each octave where an instrument is tuned in pure scale or by justintonation, is not practical, the current state of electronics nowpermits an electronic digitalized or keyboard instrument to be tuned inpure scale in every key and thereafter conveniently switched from key tokey as desired. The present invention provides such a capability and isthus a substantial advance in the art. According to the presentinvention, out-of-tuneness in electronic digitalized instruments isvirtually eliminated and the instrument Schrecongost et at.; 3,443,017to Jones; 3,458,642 to Leslie; 3,484,529 to Moore; 3,490,327 to Volpe;3,499,090 to Meyer; 3,520,982 to Malmfors; and 3,590,129 to Freeman.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a method of tuning a digitalized electronic instrument in purescale in every key.

Another object of the present invention is to provide a digitalizedeleectronic instrument capable of playing in pure scale in every key andalso equal temperament by a switching arrangment.

Still another object of the present invention is to provide apparatusfor adapting a conventional electronic digitalized instrument to becapable of being tuned in more than one key and played in such keys.

Still further, another object of the present invention is to provide anelectronic digitalized instrument capable of playing in every key, bothmajor and minor with switching means for changing from key to key.

Generally speaking, the method according to the present inventioncomprises the steps of providing an electroic digitalized instrumenthaving tunded tone generators associated with the digitals; electricallyassociating frequency modifier means with said tone generators, saidmodifier means controlling the pitch of tones produced by saidgenerators, said frequency modifier means having key switching meansassociated therewith, and setting said modifier means for each generatorin each key, whereby said instrument may be played in tune in more thanone key.

More specifically the keyboard or digitalized instrument may be ofconventional type. Preferably, the tone generators of the instrument arefirst tuned in a particular key, middle C, for example. Thereafter,means are electrically associated with each of the tone generators tovary the output frequency thereof and thus slightly vary the pitch ofthe tone produced by the generator. The frequency modifier means arethen set to produce a tone of a particular pitch for each key. Switchingmeans are further provided with the frequency modifier means so as togroup the modifier means in a predetermined fashion for the particularkey, whereby only the particular modifier means for the particular keyare actuated to influence the tone generators. Thereafter, upondepressing a digital of the instrument, the tone produced will bedetermined by the influence of the modifier means on the generator forthe particular digital. in this fashion, 156 notes per octave may beprovided, including the equally tempered and justly intoned notes, andthus provide an instrument capable of great flexibility. Insofar as theinstrument per se is concerned, the frequency modifier means andv thelike being electrically associated therewith have no effect on theinstrument insofar as movement up and down the scale is concerned, i.e.,from octave to octave. Such is conveniently handled by the standardfrequency dividing networks normally utilized in the instrument 0 a bywhatever means provided.

The tone generators are those conventionally used with the electronicorgan and are generally Hartley Colpitts type oscillators. Thefrequencymodifier means are associated with the oscillators so as to controlcurrent being supplied thereto. Current to the oscillators may be addedor deleted from the base of a transistor in the oscillator circuitwhereby the DC. operating characteristics of the oscillator are alteredto produce a tone having a slightly varied pitch. Also, a diode may beconnected in series with a capacitor across the tuning network of theoscillator with current to the diode being controlled whereby the A.C.operating characteristics of the oscillator, are altlered while the D.C.characteristics remain substantially constant. The system thus enablesthe tone generators to produce a sound of a particular pitch in aparticular key. Depending upon the system employed for tuning, certainof the notes may be duplicates with the same note in one or moreadjacent keys. As such, one frequency modifier means may be actuated forseveral keys, or a modifier means may be provided for each generator ineach key desired. Under any circumstances, when a key is selected, apredetermined group .of modifier means are actuated such that depressionof a digital produces the predetermined frequency for the key in whichthe instrument is being played.

Generally speaking, the apparatus according to the present invention forenabling an electronic keyboard or digitalized instrument to be playedin pure scale in a plurality of keys, comprises frequency modifiermeans, said frequency modifier means being adaptable for electricalconnection to tone generators of the instrument, each tone generatorhaving a plurality of modifier means associahle therewith, and switchingmeans assocaited with said frequency modifier means, said switchingmeans actuating one modifier means only for each generator at any onetime.

Preferably the modifier means according to the present inventioncomprise potentiometers which may be individually adjusted, one at atime, to control the output frequency of the tone generator with whichit is associated whereby a tone of a slightly different pitch may beproduced by influence of the potentiometers. In certain situations, asmentioned above, it is not necessary to use a separation potentiometerfor each note in each key, though one embodimet of the present inventionenvisions utilizing l2 potentiometers for each key in which theinstrument is to be played plus 12 for the equally tempered scale.

The particular potentiometers for the various notes in a single key aregrouped bythe switching .means of the present invention. The switchingmeans may comprise one of several arrangements; For example, where l2potentiometers are utilized for each key, the switching. means is set upto actuate in sets of 12 and deactivate all of the remainingpotentiometers, either by passing from one matrix to another or thelike. Additionally, where common potentiometers are used in more thanone key, isolating diodes may be employed so as to selectively actuateor deactivate certain of the potentiometers according to the key inwhich the instrument is being tuned or played. As such, thepotentiometers are grouped such that when contact be made betweenpositive and negative supply in a particular area, a predeterminednumber of potentiometers preset to produce tones of a certain pitch areactuated and the remainder of the potentiometers are deactivated orblocked out of the circuitry.

Switch means according to the present invention generally includeselector means for determining which particular group of frequencymodifier means are to be employed for providing the proper pitch tones.The present invention is not restrictive in this area, though onepreferred embodiment of the selector arrangement is a mechanicalarrangement utilizing an appropriate number of contacts for positive andnegative supply terminals, one positive and one negative contact beingprovided for each key in which the instrument is to be played.Electrical contact means are further provided on a nob or at individualswitches so as to mechanically provide current through one set ofpositive and negative terminals and thus actuate predetermined modifiermeans. Also preferred as a selector means according to the presentinvention is a single octave keyboard that is associated with circuitryto electrically switch from one group of modifier means to another groupso as to influence the tone generators according to the key in which theinstrument is to be tuned or played. Circuitry for this particulararrangement is again not restrictive, but preferably contains integratedcircuit RTL NOR gates that are connected to power switching transistorsfor each particular modifier means group. Moreover, a reset circuit isalso incorporated among the grroups of gates and so as to actuate onlythe circuit corresponding to the note depressed on the one octavekeyboard while deactivating the remainder of the circuits.

The various potentiometers or other frequency modifier means for eachtone generator each feed into a single connector for association withthe tone generator. Only the particular potentiometer of interest is,however, actuated at any one time if the output of the generator is tobe changed. As such, the apparatus according to the present inventionamay be conveniently maintained in a small housing with one lead pertone generator extending into and connected to the conventionalelectronics of the digitalized instrument. Any conventional instrumentmay thus be conveniently adapted to play in pure scale in all keys aswell as in the equal tempered scale by the apparatus of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. '1 is a circuit'diagram'of anoscillator, representing a conventional tone generator being modifiedaccording to the teachings of the present invention.

FIG. 2 is a further circuit diagram of a modifieed oscillator showinganother embodiment of the present invention. I

FIGS. 3, 3A and 3B are circuit diagrams of potentiometer groupings andswitching means according to the teachings of the present invention.

FIG. 4 is a circuit diagram of yet another frequency control meansgrouping according to the teachings of the present invention.

FIG. 5 is a schematic circuit diagram of an electronic switchingmechansim according to the teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As mentioned above, the presentinvention enables a digitallized electronic instrument to play in purescale in all keys and in equally tempered scale. Having developed anapparatus suitable for realization of such, the particular pitch of eachnote in each key must thus be established. Pitch of a note in aparticular key will vary insofar as the frequency is concerned with theparticular starting point, though the interval between notes in aparticular key can be established. Table I, set forth below, illustratesone set of values useable for the chromatic scale with just intonationand also the equally tempered intonation values for comparison purposes.

TABLE I other instruments or media which can be easily shifted up ordown as necessary, such as the human voice, the key note borrowingpresents no particular problem. .1 t E i '11 T d us qua y empere conunctive use of the 1nstrument with a fretted or a Unison [/1 1.0 5 fixedtune instrument such as a guitar or piano, for exg 'g ig 3% 1:93;;ample, does provide a problem since it is desirable to Minor Third 6/51.1892 have the average pitch remain constant through all the y gf 2;;{-33% keys. As such, the note for each key should be tuned Trimne 5 32 1142 separately, resulting in 144 distinct pitches per octave Fifth 3/2144983 instead of the 37 utilized in Table 11. Moreover, as men- MmorSlxth 8/5 1.5874 b Sixth 5/3 16818 tloned above, 1t 1s also deslra 1e toprovide the capab1 M or Se nth W 17818 ity for the instrument to betunable to the equally temg ig' (Malor) 1 6 pered scale, thus adding 12additional pitches to arrive at a total of 156 pitches per octave.

15 A new system of deriving sharp notes has also been It a definitevalue is assigned to one note, C, for exdeveloped which removes thedisadvantages set forth ample, values can be established for thedigitals of the with respect to Table 11. In Other Words, the Center Ofkeyboard as illustrated under vertical column C of tonality ismaintained very constant and the sharp keys Table 11. Furthermore,vertical column C may be exdo not become sharper or the flat keysflatter with panded through the circle of fifths or fourths taking themovement of the scale. According to the improved sysvaluc ofthe unisonfor the new key from its note value tem of tuning, note intervals areset forth below in from the previous key, whereby the note values forTable 111. each note in a new key, relaltive to the original C may Table111 depicts note intervals derived by application be calculated. Thesevalues are set forth in Table 11. of the low of combination tones. Justtuning was previ- TABLE 11 NOTE INTERVALS-JUST INTONATION -KEY EQUALLY0' A E B F c o o A E B F NOTE TEMPERED C 1.0 160 80 80 1 1 1 1 1 81 812025 32805 81 81 81 l 1 1 1 1 80 80 2048 32768 C# 1.0595 256 256 256 1616 25 135 135 135 415. 2187 2187 243 243 243 15 15 24 128 128 128 3842048 2048 D 1.1225 800 10 10 1O 10 9 9 9 9 9 729 729 729 9 9 9 9 8 8 8 88 640 640 D# 1.1892 32 32 32 32 32 6 6 6 1215 1215 1215 1215 27 27 27 2727 5 5 5 1024 1024 1024 1024 F 1.3348 320 320 4 4 4 4 4 27 27 675 1093510935 243 243 3 3 3 3 3 20 512 8192 8192 F# 1.4142 1024 1024 64 64 45 4545 729 729 729 I 729 729 45 45 18 32 32 32 32 512 512 512 G 1.4983 40 4040 40 3 3 3 3 I 3 243 243 675 27 27 27 27 2 2 2 2 2 160 160 4096 G#1.5874 128 128 128 128 8 8 8 405 405 405 405 6561 81 81 81 81 5 5 5 256256 256 256 4096 ously based on the diatonic scale only. Chromaticinter-. vals, while called just were actually out of tune hecuase ofincorrect combination tones produced thereby. The below improved systemproduces correct combination in both major and minor intervals andallows a sense of melodic correctness which was not experienced bychromatic notes by provious just standards.

TABLEIII JUST lNTONATlON NOTE lNTERVALS c 1/1 c#. 135/128 9/8 o# 19/161-: 1 /4 F 4 3 M 45/32 0 3/2 o# 304/192 A 5/3 A# 57/32 The tuning planfor the key ofC based on the above intervals is as follows: C-E-G,F-A-C, G-B-D, F to D, C to F ,G toC# ,D# toG ,andA# to D# When the keyof C is tuned as set forth above, certain intervals appear to be out oftune in the key of C. This improved system for accidental note tuning isbased on combination tones and the beats and chords in the key of Cactually produce perfectly tuned combination tones. In some instances,fundamental tones react with combination tones to produce even lowercombination tones. For example, for a C minor chord, C and E produce alower combination tone ofG and E and G produce an apparently out of tuneE natural, but the out of tune E natural combines with the fundamental Eand produces a low C.

Utilization of the intervals set forth in Table III, as mentioned above,maintains a constant center of tonality and further. all scales can betuned from only 38 distionship remain constant as does the center oftonality;

Differently from Table II, Table IV is indicated in subscript. In thisparticular arrangement, the key note, that is the note for the key inwhich tuning is desired is the starting point, and like numberedsub-scripts represent like intervals.

TABLE 1v IMPROVED JUST INTONATION PITCH SELECTION D A E 13 F c o o A E BF# 3 3 3 2 1 c 1 2 2 2 1 1 1 1 2 '2 1 C1# 1 1 1 1 3 3 3 3 3 3 2 D, 1 1 14 4 4 1 -1 1 1 1 o,# -1 2 2 2 2 2 3 3 2 2 1 E, 1 4 4 4 4 4 2 2 3 3 1 3 33 3 1 1 1 2 2 2 1 1=,# 1 1 1 3 3 3 2 2 2 2 -1 o. 1 1 3 3 3 1 1 1 1 4 1o,# 2 2 2 2 2 3 4 2 2 2 1 A 3 3 3 3 3 3 3 1 1 1 2 A.# 1 1 1 1 2 2 2 2 23 1 13 1 1 4 4 4 4 Having thus set forth two preferred arrangements fortuning the digitalized electronic instrument in pure scale, theapparatus and method of the present invention will now be described indetail, making reference to the Figures.

FIG. 1 illustrates a typical transistor oscillator in the Hartleyconfiguration which is exemplary of tone generators for digitalizedelectronic instruments. In FIG. 1,

however, the oscillator has been modified to vary the frequency outputtherefrom according to a preferred arrangement of the present invention.The oscillator generally indicated as 10 thus includes a transistor 11with the base and emitter having resistors R and R, in series therewithand the base having resistors R and R in series therewith. The tuningnetwork of the oscillator contains two capacitors C, and C in additionto a tunable coil L A connector 12 leads into the base of transistor 11and has a resistor R, therein. Connector 12 is further associated at anopposite end thereof with a number of tuning controls, illustrated bythe controls, C C and C As will be described in detail hereinafter,depending upon actuation of the switching network, C C or C etc. will beactuated in a particular key so as to provide input to oscillator 10through connector 12 and resistor R Depending upon the input, thefrequency output of oscillator 10 will be varied slightly so as toslightly vary the pitch ofa note being produced by depression of thedigital C in the particular key being played. Insofar as' the presentinvention is concerned,

the electrical means for converting oscillation tothe In the particulararrangement as shown in FIG. 1, the

current from controls C C or C is influencing the current at the base oftransistor 11 to alter the DC. operating characteristics of theoscillator. According to the embodiments shown in FIG. 1, the particulartuning control is selected and the remainder of the tuning controlsomitted through the use of isolating diodes for those tuning controlsother than C The utilization of this particular scheme of operation willbe further described herein.

Making reference to FIG. 2, a further Hartley oscillator generallyindicated as 20 is illustrated as being adapted to vary the frequencyoutput of the oscillator so as to change the pitch of a tone generatedthereby in a digitalized electronic instrument. Oscillator 20 generallydiffers-from the oscillator illustrated in FIG.

, l, in that, a capacitor C, and a diode D are connected in series andareparallel to the tuning network. .A connector 212 having a pluralityof resistors therein is associated with diode D at one end and with thekey switching network at an opposite end. Depending upon the tuningcontrol actuated, current passes through connector 212 and changes theresistance of diode D A change in the resistance of diode D, causes aproportional effect in capacitor C, which alters the AC. characteristicsof oscillator 20, while the DC. characteristics of oscillator 20 remainsubstantially constant. A lesser amount of current passing throughconnector 212 operates to create a greater frequency output fromoscillator 20 thus slightly raising the pitch of a tone generatedthereby.

One preferred arrangement will now be described for actuating thedesired controls to influence tone generators of the digitalizedinstrument and thus produce tones of particular pitches in particularkeys. In essence, FIGS. 3, 3A and 3B represent three separate .controlmatrices with FIG. 3 representing the flat key diode matrix, FIG. 3A themiddle C diode matrix and FIG. 3B the sharp key diode matrix. The threematrices in operation would be positioned side by side or otherwise withsuitable switching means associated therewith. The switch means wouldmake contact with certain of the terminals thus actuating certain of themodifier means while disassociating the remaining modifier means (tuningcontrols), whereby the tone generators will be influenced by theoperational modifier means only.

As will be further pointed out hereinafter, the switching means foractuating and/or deactivating the tuning controls associated with thevarious keys can be any suitable switching arrangement that will makecontact at the appropriate points. For example, a rotatable selector maybe provided, rotation of which moves a pair of electrical contactsacross the span of the matrices, the contacts on the selector switchmaking contact with the positive and negative supply terminals of thematrices at the particular points indicated on the Figures. Referringback to FIGS. 1 and 2, it is pointed out that the controls C Cand C areconnected to a single lead into the oscillator. Such would likewise bethe case with respect to FIGS. 3, 3A and 3B, in that, all of the Ccontrols would be connected into one lead into the C tone generator.Such connection has not been shown on FIGS. 3, 3A and 33 so as tosimplify the diagrams. In each case, the lead would be associated withthe center tap of the potentiometers.

In FIGS. 3, 3A and 38, note that middle C is not connected to either ofthe other matrices. As such, once the instrument is tuned in pure scalein the scale of C, each note will produce a tone in a pitch ofC unlessinfluenced by a further control. Note also, for example, that in the keyof F, only A and D are influenced. In this situation, all of the notesof the octave would be in the same pitch as in the scale ofC except forA and D. In both ofthese situations, controls A and D respectively wouldinfluence the oscillator for the A and D tone generators so as toproduce a tone of slightly different pitch. Similarly, with the otherkeys, only certain tone generators are affected and those not listedwould produce tones according to the pitch in the scale of C.

According to FIGS 3, 3A and 38, each tuning control is preferably apotentiometer bracketed by isolating diodes so as to precludeinadvertent actuation of same. The isolatingdiodes possess a greaterreverse breakdown than the supply voltages. Moreover, while as shown inFIGS. 3, 3A and 3B various groups are produced again by isolatingdiodes, it is also possible to have further isolating diodes connectedwith each control. The grouping arrangement, however, reducessubstantially the number of diodes required and is thus most preferred.Likewise, other possible diode variations are conceivable, though notspecifically illustrated herein. Still further, as mentioned above, eachkey may be provided with 12 separate frequency moditier means, one foreach note of the scale. With such an arrangement, once the instrument isbeing played or tuned in a particular key, only the controls in that keyare actuated and all of the remaining controls receive no power. Each ofthe tone generators for the various digitals is thus influenced by aseparate potentiometer in each key. While notparticularly illustratedfor all keys, each key circuit would take the form as shown in FIG. 3Afor middle C. In other words, instead of providing one matrix havirg 12controls for middle C, each key would have 12 controls associatedtherewith, thus providing a system with 144 controls forjust intonationor 156 controls for just intonation and equally tempered scale. Stillmaking reference to FIG. 3, assume that the instrument is to be playedin the key of B flat (B A positive voltage from the positive supplypasses through the diode 31 and actuates controls 8,, G and CSimultaneously, diodes 32, 33 and 34 will be reversed biased thusdeactivating G D F,, E and C from influencing the tone generators towhich they are connected. Hence, other than B G and C middle C tuning ofthe other notes would prevail. Likewise, when switching to another key,certain of the controls will be actuated while others will bedeactivated according to the particular arrangement for achieving justintonation of the instrument.

FIG. 4 illustrates another arrangement for the frequency modifiers forsharp keys according to the pres ent invention. The arrangement of FIG.4 does not duplicate middle C and the flat keys since both would bedesigned according to the same scheme. The arrangement of FIG. 4performs in a manner very similar to FIGS. 3, 3A and 38, though sinceduplicates of modifler means are not shared as often as in the groups ofthe FIG. 3 arrangement, a substantially larger number of potentiometersand diodes are necessary.

FIG. 5 illustrates a particular electronic switching mechanism forshifting from key to key and thus actuate the desired frequency modifieror control means for, the particular key selected. A key switch 50 iselectrically associated with integrated circuitry containing RTL NORgates (resistor, transistor, logic) gates 51, which, in turn, isconnected to a power switching transistor circuit generally indicated as60. Switching transistor circuit 60 is electrically associated with thepositive and negative contacts along the diodematrices as indicated bythecontacts for the various keys. In actuality, one RTL NOR circuit andpower switching transistor circuit is provided for each key in thesystem. Furthermore, a reset circuit generally indicated as is alsoprovided and is electrically associated as shown in each of the RTL NORcircuits. The reset circuit deactivates all of the RTL NOR circuitsexcept for the one for which the particular key 50 is depressed. Forexample, one circuit for each noteof the scale and one for equaltempered tuning, when the equal tempered key 50 is depressed, the RTLNOR circuit for equal tempered scale is actuated by providing a positivevoltage at point 52 which, in turn, actuates power switching transistor60 to actuate positive and negative supply to the equal temperedswitching network. Simulateously, the reset circuit 70 removes voltagefrom like points 52 of all other RTL NOR circuits except for the one forequal temperament. All remaining power switching transistor networks ofthe system are then deactivated until another key is depressed.

Utilizing the electronic switching arrangement of FIG. 5, a singleoctave keyboard may be provided, with each note representing one key.Depression of the particular digitalon the keyboard would then actuatethe frequency modificr'means for the key. As further illustrated in FIG.5, an indicating lamp 62 is provided which will illuminate when thepower switching network is actuated and thus indicate the particular keyin which the instrument is set to be played.

A preferred tuning arrangement includes tuning an instrument, such as anorgan, having 12 tone generators in just intonation in the key of C.Thereafter, the frequency modifying apparatus of the present inventionis connected to the organ such that one lead is electrically associatedwith each tone generator. Thereafter, the organ is returned in everydesired key, for example, all of the keys of the scale, Tuning isaccomplished by setting the selector switch to the desired key fortuning which incorporates preselected frequency modifier 'means ashereinbefore mentioned while leaving other of the tone generators astuned in the key of C. The particular tone generators having controlsassociated therewith are then tuned by simultaneously depressing certaindigitals and listening to the beat frequencies and combination tonesproduced. In the event a beat is produced, the frequency control meansis adjusted by movement of the center tap of the potentiometer until thebeat disappears. At that point, the particular tone generator is in tunein the particular key. This sequence is repeated for every key in whichit is desirable to tune the instrument. Thereafter, the instrument maybe indiscriminately played in any desired key merely by movement of theselector switch to the particular desired key. At that point theswitching network automatically actuates the prescribed control meanssuch that when a digital is depressed the tone generator for theparticular digit will produce tone of a particular pitch, either thepitch forjust intonation in the key ofC or for a modified pitch.

As also mentioned hereinbefore, once the tone generators of thedigitalized electronic instrument are tuned in pure scale utilizing thetechniques according to the present invention, movement up and down thekeyboard is handled by conventional electronics in the instrument.

Having described the present invention in detail, it is obvious that oneskilled in the art will be able to make variations and modificationsthereto without departing from the scope ofthe invention. Accordingly,the scope of the present invention should be determined only by theclaims appended hereto.

What is claimed is:

1. Apparatus for enablingan electronic keyboard instrument to play invarious keys comprising:

a. a plurality of tone generators, said tone generators beingelectrically associated with digits across said keyboard, each generatorbeing associated with only one digit per octave; and

a plurality of frequency modifier means associated with each tonegenerator, each said modifier means being adjustable according topredetermined intervals to cause the generator to emit a sound of aparticular pitch, said modifier means being grouped according to aparticular musical scale, and electronic switching means associated withsaid modifier means to activate certain modifier means only in each key,said switching means comprising a plurality of individual actuatormeans, each, actuator means having an integrated circuit coupledthereto. said integrated circuits containing RTL NOR gates and powerswitching transistors coupled thereto, each said power switchingtransistor being further coupled to one group of modifier means wherebyactuation of one of said integrated circuits actuates only the group ofmodifier means to which the power switching transistor for said acutatedintegrated circuit is coupled.

2. Apparatus as defined in claim i wherein l2 integrated circuits arepresent and wherein a reset circuit is electrically coupled to saidpower switching transistor of said integrated circuit, said resetcircuit causing removal of voltage from all power switching transistorsother than the one coupled to a selected actuator means, therebydeactivating all of said remaining- C 1 1 c# 135/128 D 9/8 with theremaining keys being grouped and predetermined using sub-script insteadof fractional intervals, maintaining a constant center of tonality andinterval relationship and using as a starting point a particular notefor the key in which tuning is desired, as provided in Table IV, saidpotentiometer frequency modifier means having isolating diodespositioned on opposite sides thereof and coupling said potentiometersand a power supply, whereby in a selected key the grouping ofpotentiometers for said key influences the tone generators for eachdigit to emit a justly intuned sound.

4. Apparatus as defined in claim 3 wherein each tone generator has 12potentiometers coupled thereto.

5'. Apparatus for enabling an electronic keyboard instrument to play invarious keys comprising:

a. a plurality of tone generators, said tone generators beingelectrically coupled with only one digit per octave;

b. a plurality of potentiometer frequency modifier means electricallycoupled to each tone generator,

, said potentiometers being adjustable according to predeterminedintervals, said potentiometers further being grouped according to aparticular musical scale and having isolating diodes located on oppositesides thereof and said diodes being connectable to a source of powersupply; and

switching means to connect one group of said potentiometers only to saidsource of power supply whereby said connected potentiometers influencethe tone generators to which they are coupled, while isolating diodespreclude interference from the other of said potentiometers.

6. Apparatus as defined in claim 5 wherein said potentiometers areadjusted according to the intervals set forth in Table I].

1. Apparatus for enabling an electronic keyboard instrument to play invarious keys comprising: a. a plurality of tone generators, said tonegenerators being electrically associated with digits across saidkeyboard, each generator being associated with only one digit peroctave; and b. a plurality of frequency modifier means associated witheach tone generator, each said modifier means being adjustable accordingto predetermined intervals to cause the generator to emit a sound of aparticular pitch, said modifier means being grouped according to aparticular musical scale, and electronic switching means associated withsaid modifier means to activate certain modifier means only in each key,said switching means comprising a plurality of individual actuatormeans, each actuator means having an integrated circuit coupled thereto,said integrated circuits containing RTL NOR gates and power switchingtransistors coupled thereto, each said power switching transistor beingfurther coupled to one group of modifier means whereby actuation of oneof said integrated circuits actuates only the group of modifier means towhich the power switching transistor for said acutated integratedcircuit is coupled.
 2. Apparatus as defined in claim 1 wherein 12integrated circuits are present and wherein a reset circuit iselectrically coupled to said power switching transistor of saidintegrated circuit, said reset circuit causing removal of voltage fromall power switching transistors other than the one coupled to a selectedactuator means, thereby deactivating all of said remaining powerswitching transistors.
 3. Apparatus for enabling an electronic keyboardinstrument to play in various keys comprising: a. a plurality of tonegenerators, said tone generators being electrically coupled with digitsacross said keyboard, each generator being coupled with only one digitper octave; and b. a plurality of potentiometer frequency modifier meanselectrically coupled to each tone generator, said modifier means beingadjusted according to the following intervals in a key of C of 4.Apparatus as defined in claim 3 wherein each tone generator has 12potentiometers coupled thereto.
 5. Apparatus for enabling an electronickeyboard instrument to play in various keys comprising: a. a pluralityof tone generators, said tone generators being electrically coupled withonly one digit per octave; b. a plurality of potentiometer frequencymodifier means electrically coupled to each tone generator, saidpotentiometers being adjustable according to predetermined intervals,said potentiometers further being grouped according to a particularmusical scale and having isolating diodes located on opposite sidesthereof and said diodes being connectable to a source of power supply;and c. switching means to connect one group of said potentiometers onlyto said source of power supply whereby said connected potentiometersinfluence the tone generators to which they are coupled, while isolatingdiodes preclude interference from the other of said potentiometers. 6.Apparatus as defined in claim 5 wherein said potentiometers are adjustedaccording to the intervals set forth in Table II.